In recent years, a shift of an operating radio frequency has been getting higher in a wireless communication system. As a matter of fact, the radio frequency band used in an in-vehicle radar system has reached near 100 GHz. A semiconductor circuit used in a system in such a radio frequency band is required to have a necessary radio frequency characteristic, which necessitates an expensive base material such as GsAs and a dedicated process, requiring a considerable manufacturing cost that is proportional to the chip area. For this reason, a development of a discrete circuit has been progressing in which only the semiconductor part that is indispensable for achieving the desired performance is made into a bare chip, and a peripheral signal input/output circuit, a functional circuit, and the like are built on an external substrate made of inexpensive organic resin or ceramic, to reduce the cost of the entire circuit.
In a diode chip used in a conventional discrete circuit, a configuration is mainly used in which a diode device and a connection pad that is the minimum needs to connect each terminal of the diode and a functional circuit on the external substrate are provided, to minimize the chip area (see, for example, Nonpatent Literature 1).
Nonpatent Literature 1: M/A-COM Product Catalog, such as model “MA4E1318”, “ONLINE”, “Searched on Feb. 25, 2007”, Internet <URL:http://www.macom.com/DataSheets/MA4E1317—1318—1319.pdf>